Images captured by a NASA science satellite reveal the star Mira has left in its wake a comet-like tail that is some 13 light years long — more than 120 trillion kilometers. It doesn't show up in the wavelengths of visible light, which is why it's a phenomenon that's never been seen before.

The Galaxy Evolution Explorer satellite, known as Galex, was launched four years ago with the aim of studying the history of the universe, using a telescope equipped with ultraviolet detectors. Finding a gigantic tail on a fast-moving star was not something astronomers had anticipated. Chris Martin, the principal investigator on Galex, announced the discovery.

MARTIN: "The Galaxy Evolution Explorer has discovered that Mira has a vast, turbulent tail stretching across interstellar space. And it's truly remarkable that this star, which has been studied for centuries, has surprised us with a completely new and unexpected phenomenon."

Mira's "tail" is composed of carbon, oxygen and other chemical elements. The discovery may help scientists understand how old, dying stars like Mira shed material that is later incorporated into new stars and planets. The astronomers calculate that the oldest parts of the tail were left behind tens of thousands of years ago, as the star grew and gravity weakened farther from its center.

MARTIN: "In fact, if we had had, 30,000 years ago — If Neanderthal man had had ultraviolet eyes and could look above the atmosphere, he could have seen the beginning of this tail forming."

The age of the tail makes it something of a time capsule, says Columbia University astronomer Michael Shara, like the rings of a tree.

SHARA: "Because we have this tail that was generated over 30,000 years, we can look at small individual pieces of the tail and deduce what the mass loss rate was like and what the chemistry along the tail was, which gives us some hint as to the differentiation of elements in the atmosphere of Mira before it started to shed mass."

In addition to the tail, images from the Galex satellite show a curved shock wave in front of Mira as it speeds through the surrounding space at 130 kilometers per second. Astronomer Mark Siebert of the Carnegie Institution says that the bow shock, as they call it, and the random-looking tail behind the star resemble a picture of a bullet in supersonic flight.

SEIBERT: "In front of the bullet there's a leading shock, much like Mira's bow shock. And then trailing the bullet there's also a classic turbulent wake, which is very reminiscent of the structures that we see behind Mira."

Seibert says Mira is a very common type of star, so it may be that this kind of tail is actually not very rare and that more will be discovered. In any event, this one is the first.

Shara, the Columbia University astronomer, says the new and completely unexpected discovery is an example of what can happen as astronomy advances.

SHARA: "Any time astronomers take a look at a new part of what we call observation space — that is, they start using a telescope which has much better angular resolution like Hubble, or much greater sensitivity in the ultraviolet like Galex, or a very large field of view like Galex — they tend to find something new, and that's exactly what's happened here."

The astronomers say they are really just beginning to study this huge structure. They published their discovery in the journal Nature.

For probably a century now, images of the future have included personal flying machines, aircraft that would zip over crowded roads — or go where there are no roads. But you probably still don't have a little airplane sitting by your front door or a helicopter on the roof. I know I don't. It may be just a dream, but the dream has never been closer to reality thanks to the convergence of aviation and information technologies.

To spur the development of PAVs — personal air vehicles — NASA is contributing $2 million in prize money for a series of annual competitions aimed at promoting fast, safe, affordable and environmentally-friendly, on-demand aviation.

NASA is better known as the U.S. space agency, but the first A in its name stands for aeronautics, and the agency has always been involved in aviation research, even if those programs are overshadowed by its space missions.

So after a week-long competition in California, NASA this week announced $250,000 in prizes to some of the pioneers whose planes were relatively small, relatively thrifty, and easy-to-fly. The contest was adminstered by the Comparative Aircraft Flight Efficiency Foundation. I asked Brien Seeley, president of the CAFE Foundation, as its known, to explain what a personal air vehicle is.

SEELEY: "The idea is that the vehicle is easy to fly, it is fairly fast, it gets excellent fuel economy, and it can land in a very short space."

Q: So is this the sort of transportation system that an ordinary person might use?

SEELEY: "We expect that it can become so with the help of people like Ken Goodrich at NASA-Langley [Research Center], who's working on a naturalistic flight deck that will give so much electronic assistance to the pilot that the task of flying becomes very similar to that of driving a car."

Q: I've never taken flying lessons but from what I understand, it is considerably more difficult than driving a car — a lot more controls, and that third dimension you always have to be aware of.

SEELEY: "Yes, the modern computer flight deck, though, is going to make this much, much easier. If you've ever driven a video game in which you pilot the vehicle down a highway or road with simulated perspective, that's the kind of depiction that the pilot will be given in the PAV of the future. Literally it will be like driving through a tunnel and you simply stay in the tunnel and it assures you will reach your destination without any traffic conflict."

Q: Well, let's talk about the competition. It was, I guess, a week-long event?

SEELEY: "They had to compete for fuel efficiency or miles per gallon, and they had to compete for shortest runway, for the quietest noise both in the cabin and emitting to the community, for the best handling qualities, and finally for their top speed. All these separate events were combined to determine an overall winner who this year won a $100,000 cash prize."

Q: And that was Vance Turner of Rescue, California. What was his aircraft like?

SEELEY: "He had an aircraft that was made in Slovenia. It's called the Pipestrel Virus. It's very quiet. It's very efficient. It's very fast. The Pipestrel's selling price, we understand, ranges from about $75,000 up to over $100,000, depending upon the options and choices that are made. And the goal, ultimately, is for a mass production to bring the range of these vehicles down to the price of, perhaps, a luxury sedan."

Q: It seems that the idea of a personal aircraft has been part of, not just science fiction but sort of legitimate futurist thought for a long time, for decades really. It always seems to be just over the horizon. We never seem to quite get there. Is it different now, or what is different now?

SEELEY: "What's different now, essentially, is the all-weather capability made possible by the global positioning system, the satellite system, along with the global mapping system that has mapped the terrain of the Earth to high precision. And in addition has taken satellite photographs of the Earth that are photorealistic. And when all that is combined into one giant 'brain,' it can literally depict a clear, photographic-like image in the cockpit when flying at night in the rain, and you can see the land, landscape, and landing sites ahead of you just as if it were broad daylight. That enablement is really what opens up the use of PAVs for common travel by everyday people."

Brien Seeley of the CAFE Foundation says the annual competition will return to Sonoma County Airport in California next August.

The relationship between eating red meat and getting colon cancer has been the subject of numerous studies over the years. According to the U.S. National Cancer Institute, some studies have shown that a diet high in fat, proteins, calories, and meat increases the risk of colorectal cancer, but other studies have not. Which isn't to say there aren't other good reasons to avoid that kind of diet, just that the impact on colon cancer is inconclusive.

But what about a diet for people who already have colon cancer? A new study indicates that colon cancer survivors may increase their risk of recurrence or death by eating a so-called Western diet, high in fat and processed foods. While the findings are not definitive, VOA's Jessica Berman reports experts say the study offers food for thought.

BERMAN: In addition to setting the stage for the development of colon cancer, scientists have now found that a diet high in red meat and processed foods can lead to relapse or death in colon cancer patients who are undergoing treatment.

Researcher Jeffrey Meyerhardt of the Dana-Farber Cancer Institute in Boston, Massachusetts and colleagues looked at the impact of two distinct diet patterns, one healthy and one not, in a group of one-thousand patients with stage-three colon cancer, cancer that has spread to the lymph nodes.

The patients were part of a clinical trial of people receiving chemotherapy in the six months after surgery, and they kept detailed diaries of what they ate during this time. Those who reported eating a healthy diet consumed large amounts of fruits, vegetables, poultry, and fish. Those who ate the so-called Western-style diet frequently consumed red meat, fat, refined grains and dessert.

Five years later, 324 patients had a recurrence of cancer and 223 patients had died. Investigators found that those in the Western group with the worst diet were three times more likely to have a recurrence and die of colon cancer than those in the Western group who ate less junk food.

MEYERHARDT: "People who have a higher Western pattern diet have an increased risk for recurrence, but that does not mean people who have very little of a Western pattern diet have no chance for recurrence. It is just relatively, it is an additional thing to improve people with colon cancer's outcomes."

BERMAN: In contrast, among those patients who ate a healthy diet, there was no increased risk of recurrence and death.

Meyerhardt says the study makes clear what the culprit is.

MEYERHARDT: "It is not really increasing the amount of fruits and vegetables, but really trying to reduce the amount of red meat intake and fatty foods and sugary, 'desserty' foods...."

BERMAN: The study on diet and colon cancer is published this week in the Journal of the American Medical Association. Jessica Berman, VOA News, Washington.

If you live in an urban area, like I do, it's easy to lose the connection to where our food comes from. Ask a city kid, and they're likely to say that rice or bananas or chicken comes from the grocery store, not the farm.

But you don't have to go out to the countyside to get a taste of country life and a sense of farm history, thanks to the the miracle of the Internet and our Website of the Week.

This week, a click of a mouse takes us to Wessels Living History Farm in York, Nebraska. It was a real family farm for most of the 20th century, and now it lives on as a working farm museum, and online at livinghistoryfarm.org, where you can hear about the history of American farming from people who were there.

GANZEL: "We have approximately 400 stories on the website right now. Each of those goes into great detail about an aspect of agriculture and agricultural history. And as I said, you know, the oral history interviews bring, I think, that history to life because history really matters when you know how big events affected everyday life. So that's why the oral history interviews are so important."

Bill Ganzel created the website, and with his background in television, the high quality of the brief video interviews really stands out. Stanley Jensen talks about the threat posed by grasshoppers. Helen Bolton describes the challenge of learning to switch from horse to tractor. There's even poetry from former U.S. poet laureate Ted Kooser, who evokes a hard but romantic era in agriculture.

If you can't visit Wessels Living History Farm in person, the website lets you see what's happening out on the farm's 60 hectares.

GANZEL: "If you go onto the webcam that's on the website, you can, you know, see how those are going. And in fact one of the things that we've just put together is a timelapse movie about how the corn that was planted south of the barn, how quickly it grew. And it's pretty amazing that, you know, after germination within a couple of months it had grown to its full height."

Our Website of the Week, Wessels Living History Farm, online at livinghistoryfarm.org or get the link from our site, voanews.com/ourworld.

In the 1960s, the editor of the literary magazine "Saturday Review," was disagnosed with a fatal illness. Norman Cousins did something most patients didn't do back then: he did his own medical research and made his own decisions about his treatment. And one of the things he decided to do was watch a lot of funny movies and TV shows. He said that watching Marx Brothers movies and other funny stuff had an anesthetic effect, and enabled him to get at least a couple of hours of pain-free sleep, after which it was time for another dose of comedy.

Researchers are still studying the therapeutic value of humor, as we hear from health reporter Rose Hoban.

HOBAN: Everyone loves to laugh. But do you know what makes something funny? Philosophers and comics have wondered what constitutes humor… and so have medical researchers, because having a sense of humor can be an important coping mechanism, helping people to deal with life's frustrations and tragedies and survive them better.

Psychology doctoral student Wingyun Mak from Washington University in St. Louis set out to see whether humor could help older people cope with aging and increased illness. She started by thinking about what functions of the brain are involved in understanding humor:

MAK: "…the short-term memory, and the mental flexibility, and also the abstraction ability, we believe that these are housed in the frontal regions of the brain, and research would tell us that the frontal region is really the first to go with age."

HOBAN: So, to study these brain functions, Mak and her colleagues asked older adults to look at the start of a cartoon joke. Then they were asked to choose the 'correct' punch line from a series of answers.

MAK: "And based on the answer that they selected we can tell something about how they were interpreting the jokes. Whether or not they were understanding the pun, or the inflection of the situation, or whether or not they were just completing it in, kind of a logical, unfunny way."

HOBAN: Mak found that compared to a control group of college students, the older adults didn't 'get' the humor as frequently. She says the results don't mean that older people are humorless. She says, instead, these results give an idea of how declines in cognition impair our ability to comprehend humor.

MAK: "We're just trying to reconcile how these different processes will fit together. And so, I think something that we always talk about in terms of future directions is trying to integrate how a person's preferences or their personality, or maybe their previous life experiences, like their occupation, how do these factors play into how well or not well somebody understands humor, how well or not well somebody is able to incorporate a sense of humor into their everyday lives."

HOBAN: One thing Mak noted is that the older adults were more enthusiastic about participating in the research than were the young people. And she says they often told stories about the role humor has played into their lives.

Mak's research is published in the Journal of The International Neuropsychological Society. I'm Rose Hoban.

If you use a computer, you know it's a scary world out there. E-mail spam. Viruses. Worms. Trojan Horses. "Malware" is the generic term. Bad stuff that can infect your computer and ruin your whole day.

So let's end the program today with a few words on cyber-security from one of the top experts in the field. Prof. Sy Goodman teaches at Georgia Tech in Atlanta and he spearheaded a report on cybersecurity research for the U.S. National Academy of Sciences.

Goodman says that in spam now amounts to an estimated 90 percent of all emails. And most of that is the work of a relatively few individuals, according to the European anti-spam group, the Spamhaus project.

GOODMAN: "And Spamhaus and others estimate that there are about 200 people in the world — unfortunately a fair number of them located in the United States (or maybe that's better; we can get at them) — 200 people throughout the world who account for 75 percent of that 90 percent of all traffic that's spam."

Spam, viruses that spread online, and other hazards of the Internet, are annoying, costly, and sometimes dangerous. But despite all that, some 1.3 billion people use the Internet, and that number is growing every day, Prof. Goodman says, because the benefits outweigh the potential harm.

GOODMAN: "For the most part, for all of these people who now make up a very sizeable fraction of the world's population, the benefits are great enough for them to keep doing it, but with all of this new technology, very little of which including the original Arpanet, was designed with any security in mind. So in addition to an information revolution, which is much ballyhooed, we also have an information insecurity revolution."

The Internet began as a military project and was designed during the Cold War, with multiple pathways between users in case a nuclear attack wiped out part of the network. It had its first big growth spurt in universities, where openness and collaboration are important. The Internet that exploded on the wider public in the 1990s was easily exploited. It was designed to be robust and open, not controlled and secure.

Goodman says emerging online technology and the very design of the Internet give the bad guys tremendous leverage.

GOODMAN: "These guys are becoming innovative probably faster than the good guys. Now there's something wrong here because we have most of the PhDs on our side."

In addition to the burden on the capacity of the Internet posed by the sheer volume of spam and the potential damage from malware, Sy Goodman says the Internet can facilitate illegal off-line activites.

GOODMAN: "Terrorists of all kinds, all over the world, but especially in the more developed parts of the world, have become extremely dependent on the Internet for basic communications, for making plans, for finding information, for transferring money, for doing all sorts of things."

Sy Goodman of Georgia Tech spoke recently at the Hudson Institute in Washington. So what's the solution? Goodman says ordinary law enforcement techniques haven't been effective. He discussed the possibility of international civil regulation, like the system that governs air travel. In a draft report prepared by the National Academy of Sciences expert panel that Goodman is chairing, the recommendations include creating a greater sense of urgency about the cybersecurity problem to promote action, and increasing the technical and human infrastructure for better understanding how to face down the threat.

MUSIC: "Our World" theme

That's our show for this week. We're always interested in your comments or your science questions. Email us at ourworld@voanews.com. Or use the postal address —

Our WorldVoice of AmericaWashington, DC 20237 USA

Faith Lapidus edited the program. Felicia Butler is the technical director. And this is Art Chimes, inviting you to join us online at voanews.com/ourworld or on your radio next Saturday and Sunday as we check out the latest in science and technology ... in Our World.